Got Mud?

The state’s wetlands, important for the protection of all life, have been severely degraded over the years. Can they recover? New partnerships may slow their decline—if Mother Nature doesn’t do them in first

by Reid Champagne

(page 3 of 5)

“In the case of non-tidal marshes, we need to restore the natural floodplain that has been lost due to reclassification of land away from wetland designation,” she says.

Inland wetlands are crucial to maintaining tidal wetlands because they migrate upland to extend what’s lost to erosion on the shoreline. Think of the entire wetland ecosystem as a giant accordion. When one side, the tidal wetlands, is compressed through erosion, the other side, or non-tidal wetlands, expands and the marsh pushes upland.

But keeping land available for upland migration smacks headlong into the pressure to develop open spaces. Development often walls off land that could become part of that natural migration. Buffers—ribbons of land DNREC manages to protect environmentally sensitive areas from pollutants and nutrient runoff—protect existing wetland boundaries, but do not allow for migration.

“The key to restoring non-tidal wetlands is to take back previously developed land, restore the floodplain, and ensure that sufficient forest buffers are situated around the wetlands,” Kreeger says.
Associate professor of oceanography Christopher Sommerfield of the University of Delaware College of Marine and Earth Studies disagrees with part of Kreeger’s assessment, believing the historical picture indicates a system that is still relatively in balance.

“You’re always going to see erosion at the shoreline edge of our marshes,” Sommerfield says. “Marshes are hurt by wave energy that is normally weakened by the presence of mud flats that form in front of the shoreline. A lack of these mudflats increases the rate of erosion.”

All marshes resulted from mud flats that existed long ago. Yet the disappearance of these flats are not the main threat to the wetlands, says Sommerfield. The rate of sediment accretion, he says, is the key. Sommerfield’s lab can measure the rate of accretion, or upward development of marshland needed to sustain marsh development.

“We’ve taken core samples of our marshes, and it appears those marshes are not sediment starved,” Sommerfield says. “Their development matches what our lab results suggest development should be over time.”